Effects of Fermented Rice Vinegar Kurozu and Its Sediment on Inflammation-Induced Plasminogen Activator Inhibitor 1 (PAI-1) Increase

Plasminogen and its cleavage form, plasmin, are associated with the fibrinolytic system that is involved in fibrin degradation and clot removal. Plasmin formation is catalyzed by tissue-type (t-PA) or urokinase-type (u-PA) plasminogen activators. Plasminogen activator inhibitor-1 (PAI-1) is the primary physiological inhibitor of t-PA and u-PA, and it plays an important role in the removal of thrombi from the vascular system under thrombotic conditions. However, increased plasma PAI-1 levels suppress the normal fibrinolytic system and lead to prothrombotic states; it is a risk factor for the development of thrombotic diseases.

Kurozu is traditional Japanese black vinegar produced from unpolished rice. It is used in Japan as a seasoning agent or consumed as a health food. Kurozu-moromi (KM) is the solid sediment that arises during the production of Kurozu. Kurozu is thought to have blood thinning and antithrombotic activities but a specific effect has not been proven.

In this study, the authors examined the effects of a diet containing Kurozu and Kurozu-moromi on LPS (lipopolysaccharide)-induced increases in plasma PAI-1 levels in mice and on TNF-α (tumor necrosis factor α) increased PAI-1 production in the medium of a cultured endothelial cell line. Mice were fed with a diet containing 0.25% (w/w) concentrated Kurozu or 0.5% (w/w) Kurozu-moromi for four weeks, and then subcutaneously injected with 0.015 mg/kg of LPS in saline and sacrificed three hours later.

The present findings showed that orally administered concentrated Kurozu (CK) and Kurozu-moromi (KM) both significantly suppressed not only LPS-induced increases of PAI-1 antigen but also PAI-1 activity in mouse plasma. This indicated that orally administered CK or KM could decrease thrombotic tendencies induced by inflammation in mice. Besides, the ethanol extract of Kurozu-moromi inhibited TNF-α induced increases of PAI-1 in the culture medium of the EA.hy926 endothelial cell line.

In conclusion, Kurozu and Kurozu-moromi might contain some natural products that could decrease thrombotic tendencies in inflammation and thus have potential as antithrombotic foodstuffs.

Article by Naoki Ohkura, et al, from Japan.

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